Default to using BuildKit

[garethr]

I'm finding myself always needing to remember to add the following to my actions:

env:
        DOCKER_BUILDKIT: 1

I wonder if this should be a first-class part of the interface, rather than needing to know the environment variable? I also wonder if this should default to using BuildKit?

[zappy-shu]

Hi @garethr this is something I'd like to do as well. It shouldn't be too difficult to implement.
@nebuk89 any thoughts?

[crazy-max]

Version 2 has been merged to the main branch and is therefore available via uses: docker/build-push-action@v2 (mutable tag).

As a reminder, this new version changes drastically and works with 3 new actions (login, setup-buildx and setup-qemu) that we have created. Many usage examples have been added to handle most use cases.

And it should fix this current issue. Don't hesitate if you have any questions.

[theogravity]

With v2, do I need to use the DOCKER_BUILDKIT env variable at all? Not clear from the readme and the discussion thread here.